Glazing with optical and/or energetic properties capable of being electrically controlled

ABSTRACT

The subject of the invention is glazing which incorporates at least one electrically controllable system having variable optical and/or energy properties, especially in the form of a system comprising one or more reversible-insertion materials of the electrochromic-system type, in the form of an optical-valve or viologen-based system or in the form of a liquid-crystal or cholesteric-gel system. This glazing also includes at least one means for adjusting the optical appearance conferred on the said glazing by the said system, these means comprising at least one coating having antireflection properties in the visible.

This is a continuation application of U.S. application Ser. No.09/486,719, filed Aug. 2, 2000, now U.S. Pat. No. 6,746,775, which is a371 of PCT/FR99/01652, filed Jul. 8, 1999.

The present invention relates to glazing having electricallycontrollable optical and/or energy properties.

Thus, it relates to glazing some of whose characteristics can bemodified by a suitable electrical supply, most particularly thetransmission, absorption and reflection within certain wavelengths ofelectromagnetic radiation, especially in the visible and/or in theinfrared, or else the light scattering.

There is in fact an increasing demand for so-called “smart” glazingwhose properties may be varied.

Thus, from the thermal standpoint, glazing whose transmission/absorptionmay be varied within at least part of the solar spectrum allows thesolar heat influx into rooms or passenger areas/compartments to becontrolled hen it is fitted as the external glazing in buildings or aswindows in transportation means of the type comprising cars, trains,aeroplanes, etc., and thus it allows excessive heating of the latter tobe prevented should there be strong sunlight.

From the optical standpoint, the glazing allows the degree of vision tobe controlled, thereby making it possible to prevent glare should therebe strong sunlight, when it is mounted as exterior glazing. It may alsohave a particularly advantageous shutter effect, both as exteriorglazing and if it is used as interior glazing, for example for equippinginternal partitions between rooms (offices in a building), or forisolating compartments in trains or aeroplanes, for example.

There are many other applications: for example, glazing having variablelight transmission/reflection may be used for making rear-view mirrors,which can darken as required in order to prevent the driver of the carbecoming dazzled. They may also be used for indicating panels onroadways, or any display panel, for example so as to reveal thedrawing/message only intermittently in order to attract greaterattention.

One particularly advantageous application of the systems having variablelight absorption relates to display screens, especially all those withwhich televisions and computing hardware are equipped. This is becausethis type of glazing makes it possible to improve the contrast of theimage, especially taking the ambient brightness into account.

The advantage that such glazing may provide justifies the fact that manysystems have already been studied.

Thus, known systems allowing the light transmission or absorption ofglazing to be varied are especially so-called viologen-based systems,such as those described in Patent U.S. Pat. No. 5,239,406 or in PatentEP-A-0,612,226. These make it possible to obtain variable absorption,essentially in the visible region.

To the same end, there are also so-called electrochromic systems, theoperating principle of which will be briefly recalled: these comprise,in a known manner, a layer of an electrochromic material capable ofreversibly and simultaneously inserting ions and electrons, theoxidation states of which electrochromic material corresponding to theinserted and extracted states have a distinct colour, one of the stateshaving a higher light transmission than the other. The insertion orextraction reaction is controlled by a suitable electrical supply usinga current generator or a voltage generator. The electrochromic material,usually based on tungsten oxide, must thus be brought into contact witha source of electrons, such as a transparent electrically conductivelayer, and with a source of ions (cations) such as an ionicallyconductive electrolyte.

Moreover, it is known that, in order to guarantee at least the order ofa hundred switching operations, the layer of electrochromic materialmust be connected to a counterelectrode which is itself capable ofreversibly inserting cations, symmetrically with respect to the layer ofelectrochromic material, so that, macroscopically, the electrolyteappears as a single ion medium.

The counterelectrode must consist of a layer which is either neutral interms of colour or is at least transparent or barely coloured when theelectrochromic layer is in the bleached state. Since tungsten oxide is acathodic electrochromic material, that is to say its coloured statecorresponds to the most reduced state, an anodic electrochromic materialbased on nickel oxide or iridium oxide is generally used for thecounterelectrode. It has also been proposed to use an optically neutralmaterial in the oxidation states in question, such as, for example,cerium oxide or organic materials such as electronically conductivepolymers (polyaniline, etc.) or Prussian blue.

A description of such systems will be found, for example, in EuropeanPatents EP-0,338,976, EP-0,408,427, EP-0,575,207 and EP-0,628,849.

At the present time, these systems may be put into two categories,depending on the type of electrolyte that they use:

-   → either the electrolyte is in the form of a polymer or a gel, for    example a polymer which conducts via protons, such as those    described in European Patents EP-0,253,713 and EP-0,670,346, or a    polymer which conducts via lithium ions, such as those described in    Patents EP-0,382,623, EP-0,518,754 or EP-0,532,408;-   → or the electrolyte is an inorganic layer which is ionically    conductive but electronically insulating—these are then referred to    as “all-solid” electrochromic systems. For the description of an    “all-solid” electrochromic system, reference may be made to European    Patent Applications EP-97/400702.3 (filed on 27 Mar. 1997) and    EP-0,831,360.

Other systems use electrochromic-type reversible ion-insertion materialsslightly differently. These are, for example, so-called gasochromicsystems, in which the electrochromic material is provided with a thincatalytic layer capable of decomposing hydrogen and mounted in adouble-glazing unit on the internal gas-cavity side: by sending hydrogeninto the internal space of the double-glazing unit, tungsten oxidebecomes coloured. It returns to the bleached state by injecting oxygen,instead of hydrogen, into the internal space.

These systems having one or more reversible-insertion materials areparticularly advantageous in the sense that they allow the absorption tobe varied over a broader wavelength range than viologen-based systems:they allow variable absorption not only in the visible but also, inparticular, in the infrared, which may confer on them an effectiveoptical and/or thermal role.

Viologen-based or electrochromic systems, deposited on or associatedwith transparent substrates, form glazing whose light absorption andtransmission (as well as energy transmission) may vary within givenranges, especially ranges determined by the choice of electrochromicmaterials used and/or by the choice of their thicknesses.

Another type of “smart” glazing is formed by what is termed an “opticalvalve”: this is a film comprising a generally crosslinked polymer matrixin which microdroplets are dispersed, these microdroplets containingparticles which have the property of being aligned in a preferreddirection due to the action of an electric or magnetic field. The filmhas variable optical properties depending in particular on the potentialapplied to the terminals of the conductive layers placed on either sideof the film and on the concentration and nature of the orientableparticles. Thus, Patent WO-93/09460 discloses an optical valve based ona film comprising a crosslinkable poly-organosilane matrix and inorganicor organic orientable particles, more particularly light-absorbingparticles such as particles of polyiodides. When a voltage is applied tothe film, the particles intercept the light much less than when novoltage is applied.

Glazing with variable light scattering, the operating principle of whichis similar, is also known by the expression “liquid-crystal glazing”.This is based on he use of a film placed between two conductive layersbased on a polymeric material in which droplets of liquid crystals aredispersed, especially nematic liquid crystals of positive dielectricanisotropy. When a voltage is applied to the film, the liquid crystalsorient in a preferred direction, thereby allowing vision. When novoltage is applied, and the crystals are not aligned, the film becomesscattering and prevents vision. Examples of such films are described,for instance, in European Patent EP-0,238,164 and United States PatentsU.S. Pat. Nos. 4,435,04, 4,806,922 and 4,732,456. This type of film,once laminated and incorporated between two glass substrates, is sold bySaint-Gobain Vitrage under the brand name “Priva-lite”. In fact, it ispossible to use any of he liquid-crystal devices known by the term“NCAP” (Nematic Curvilinearly Aligned Phase) or the term “PDLC” (PolymerDispersed Liquid Crystal) or the term “CLC” (Cholesteric LiquidCrystal). These may furthermore contain dichroic dyes, especially insolution in the liquid-crystal droplets. It is then possible to jointlyvary the light scattering and the light absorption of the systems.

It is also possible to use, for example, gels based on cholestericliquid crystals containing a small amount of crosslinked polymer, suchas those described in Patent WO-92/19695.

However, all these various systems/glazing assemblies have limits whichare intrinsic to them, which limits relate especially to their opticalappearance.

Thus, in the case of electrochromic-type glazing, it is possible to varythe range of accessible values of light transmission (T_(L)) byadjusting, for example, the thickness of the layer (or layers) based ona reversible-insertion material. However, for a given system, the T_(L)range can only be shifted somewhat towards lower or higher values, andthis cannot be easily extended. Furthermore, the choice ofreversible-insertion material will have a bearing on the calorimetricappearance of the glazing both in transmission and in reflection.

The object of the invention is therefore to alleviate these drawbacks,especially by proposing novel electrically controllable glazing havingvariable optical and/or energy properties, the optical appearance ofwhich can also be varied.

The subject of the invention is glazing which incorporates at least oneelectrically controllable system having variable optical and/or energyproperties, of the type comprising a system having variable light and/orenergy transmission/absorption and/or variable light scattering. Thisglazing furthermore includes at least one means for adjusting theoptical appearance conferred on the glazing by the electricallycontrollable system. This means is advantageously in the form of atleast one coating having antireflection properties in the visible or inthe near infrared.

In order to simplify matters, hereafter this coating will be referred toas an “antireflection coating” and the electrically controllable systemwill be referred to as the “functional system”.

Combining the functional system with an antireflection coating, thecharacteristics of which may be adjusted precisely, makes it actuallypossible to modify the optical or thermal performance of the glazing.Thus, the antireflection coating may have an influence on the range oflight or solar transmission that the glazing may have with an ad hocelectrical supply: in particular, it may shift, in a controlled manner,this range towards higher T_(L) or T_(E) (energy transmission) values.Specifically, this means that, for a given functional system, theaddition of the antireflection coating will make it possible to modifyits T_(L) or T_(E) range depending on the intended application, withouthaving to modify the functional system itself. With regard to themanufacture of the glazing, this allows production which is much moreflexible and rational than if as many different functional systems asthere are envisaged applications had to be manufactured.

This is because, for some applications, the aim is to provide a stronglycolouring/absorbing effect when a voltage is applied, makingaccommodations for a certain residual coloration when no voltage isapplied (for example if it is desired to tend towards glazing having ashutter effect in the coloured state).

On the other hand, for other applications, it will be necessary for theglazing to have, when no voltage is applied, little or even no residualcoloration. This may be the case, for example, in functional systems fordisplay screens. Furthermore, it is much simpler to maintain only asrestricted a number of “standard” functional systems as possible and toadapt them by means of the ad hoc antireflection coating, which coatingis generally much less complicated o manufacture than the functionalsystems.

The antireflection coating may also allow the range of accessible T_(L)or T_(E) values to be extended. This is a very important advantagewhatever the application intended, which advantage is particularlyessential when the glazing is used to enhance the contrast of displayscreens. This is most particularly true with new televisions making useof flat-screen, plasma technology, these also being called emissive,which tend to have a much lower brightness than standardcathode-ray-tube televisions.

One advantageous embodiment of the antireflection coating consists indepositing it on at least one of the external faces of the glazing, thatis to say the faces exposed directly to the ambient atmosphere of theglazing. Both these faces may be treated or, in the case ofdisplay-screen glazing, only the face turned towards the outside of theapparatus. In a known manner, this coating may comprise a stack of thinlayers having alternately high and low refractive indices, which, by aninterference effect, tend to reduce the light reflection of the glazingto the profit of an increase in its light transmission. Examples ofantireflection stacks are, for example, known from Patents EP-0,728,712,EP-0,712,815 and EP-0,791,562.

These layers are generally made of a dielectric material of the oxidetype (SiO₂ or Al₂O₃ for the layers having a low index of less than 1.7and SnO₂, TiO₂ or Nb₂O₅ for the layers having a higher index of at least1.9) or else of the fluoride type (MgF₂ as the low-index layer) or ofthe nitride type, such as Si₃N₄ or silicon derivatives of theSiO_(x)N_(z) or SiO_(x)C_(y) type.

However, an antistatic function may also be conferred on theantireflection coating by incorporating into the coating, as a low-indexor high-index layer, a layer of a material which, from an electricalstandpoint, is at least slightly conductive. A layer of a doped metaloxide may especially be chosen, such as F:SnO₂ or ITO (tin-doped indiumoxide), which has an index of at least 1.9 to 2.0 or a layer of aconductive polymer.

The antireflection coating may also consist only of a single layerhaving a refractive index gradient in its thickness, this layer beingobtained, for example, using a pyrolysis-type deposition technique. Thishot deposition technique makes it possible to obtain layers which areparticularly durable from a mechanical standpoint, which may be veryimportant depending on the envisaged application of the system,especially so that the coating can withstand being touched, beingrepeatedly cleaned, etc. This graded-index layer has in fact a chemicalcomposition which varies through its thickness, for example graduallyapproaching a SiO₂-type composition from one of the SiOC or SiON type.

The glazing according to the invention may also include a means foradjusting the optical appearance conferred on the said glazing by thefunctional system, comprising at least one coating forattenuating/modifying the colour of the glazing in reflection (thiscoating being as an addition or an alternative to the previousantireflection coating). This is because, in some applications, forexample in the case of glazing for display screens of all kinds, it ispreferable for the colour of the glazing in reflection to be as neutralas possible, especially so that in the completely bleached state theglazing does not appear tinted at all and so that it is of a tintmodifying the colour of the image appearing on the screen as little aspossible. Since the antireflection coating makes it possible for theintensity of light reflection of the glazing to be generally lowered,this other coating may therefore complete its optical role by allowingits colour in reflection to be attenuated, in practice by lowering theC* saturation values, in she (L,a*,b*) colorimetry system, of theglazing in reflection.

This coating is advantageously in contact with the functional system, inthe form of a thin layer at least having a refractive index intermediatebetween those of the materials with which it is in contact on each ofits faces. This may especially be a thin layer having a refractive indexof between 1.6 and 1.9, especially one based on aluminium oxide Al₂O₃,on aluminium oxynitride AlN or on yttrium oxide Y₂O₃, on siliconoxycarbide and/or oxynitride SiOC, SiON, or on a mixture of at least twoof these materials, which may be deposited by vacuum technologies of thesputtering type or by pyrolysis-type technologies, the latter being mostparticularly indicated for depositing layers of silicon derivatives.

This coating may comprise not one layer, but several, especially in theform of at least two superposed layers whose average index is, forexample, between 1.6 and 1.9, for example an SnO₂/SiO₂ or SnO₂/SiO₂/SnO₂stack.

This coating may also be a layer having an index gradient through itsthickness so as to optimize its adjustment with respect to the indicesof the materials which surround it. The formation of such a graded-indexlayer using a vapour-phase pyrolysis technique (also called CVD for“Chemical Vapour Deposition”) is, for example, described in PatentWO-97/03029 (to which reference may also be made for the graded-indexlayer of the previous antireflection coating).

The glazing according to the invention may also include aprimer/tie-layer coating for the functional system with respect to itscarrier substrate, which may prove to be particularly advantageous ifthe nature of the substrate is polymeric/plastic and not mineral, of theglass type. The coating may comprise a thin metal Layer, a layer of asilicon derivative of the SiO₂ type or of a suitable metal oxide of theAl₂O₃ type. It may also be a tie-layer varnish. Advantageously, thistie-Layer coating may also be made to fulfil a role of attenuating thecolour of the glazing in reflection, like the specific coating mentionedabove, especially if it has a refractive index matching that of theplastic substrate and that of the layer of the functional system withwhich it is in contact.

The glazing according to the invention may also include a hydrophiliccoating having antimisting properties or a hydrophobic coating havinganti-rain properties on at least one of its external faces. As suitablehydrophobic coating, reference may be made, for example, to PatentsEP-799,873 and EP-692,463. It may especially be at least one layerconsisting of a composition having at least one fluoroalkoxysilane, thealkoxy functional groups of which are directly linked to the siliconatom, a system of one or more aqueous solvents and at least one catalystchosen from an acid and/or a Brönsted base. The coating may also includea primer layer promoting adhesion of the hydrophobic layer to the glass,for example a primer layer based on silanes.

The glazing according to the invention may also include a coating havingphotocatalytic properties giving the glazing antifouling properties,especially on at least one of its external faces. This may especially bea coating comprising semiconductor materials, of the crystallized oxideor sulphide type, having this type of property, especially crystallizedoxides of the ZnO, WO₃ or SnO₂ type and more particularly titanium oxideat least partially crystallized in anatase form. This type of coatingand the various ways of obtaining it are especially described in PatentsWO-97/10186 and WO-97/10185. These coatings make it possible to degradeany dirt of organic nature. They may furthermore be hydrophilic and thuspromote the removal of inorganic dirt as well.

The glazing according to the invention may also include at least onecoating having electromagnetic screening properties, especiallyscreening properties with respect to radiation emitted by emissivescreens of the plasma-screen type. This type of coating includes, orexample, at least one thin layer essentially made of metal, or of aconductive metal oxide, and/or one or more superposed arrays of metalconducting wires and/or a metal mesh.

The functional system of the glazing is, as was seen previously,generally in the form of a superposition of functional layers placedbetween two carrier/protective substrates which may be rigid, semi-rigidor flexible. It may be advantageous to use, as carrier substrate, atleast one of the rigid substrates of which the glazing is composedand/or at least one flexible carrier substrate which may be associated,by lamination, with one of the rigid substrates of which the glazing iscomposed. The functional system may also be placed on a suitablesubstrate, and then simply protected/encapsulated by an impermeableprotective coating providing it with a degree of mechanical protection.It may be an inorganic layer of the SiO₂ or Si₃N₄ type. It may also beof the polymer(s) type instead, especially in the form of a varnish(epoxy or polyparaxylylene) or of a lacquer (polyurethane orpolyacrylic). Preferably, it may be a vacuum-deposited monolayer of apolymer.

The object of the invention is also the use of the glazing describedabove as glazing for buildings, especially as exterior windows, windowsfor interior partitions or glazed doors (for example sunroofs of the“Vélux” type), and as glazing with which transportation means areequipped, especially windows for motor vehicles (sunroofs and front andrear side windows) railway windows or aeroplane windows, especially aswindscreens, windscreen top-tint strips, or cabin windows. Such glazingis also indicated for equipping display screens in order to enhanceimage contrast, especially television or computer screens. Such glazingmay also be used as protection for solar panels (satellites, for cameralenses, for spectacles for aircraft pilots, sunglasses or ophthalmicspectacles, or else as glazing suitable for the protection ofobjects/plants from heat or strong light which are sensitive thereto,for example for equipping greenhouses or shop windows.

As mentioned above, the invention thus applies to various types ofelectrochemically controllable glazing. This may be, as mentioned,glazing having variable light transmission/absorption, especially havinga viologen-based or electrochromic system, particularly of the type ofthose described in the aforementioned Patents EP-0,338,876,EP-0,408,427, EP-0,575,203 and EP-0,628,849. It is preferably in theform of a stack of functional layers comprising, in succession, apreferably transparent electrically conductive layer, a so-calledcathodic electrochromic layer capable of reversibly inserting cationssuch as H⁺, Li⁺, Na⁻, Ag⁺, a layer of electrolyte, optionally acounterelectrode in the form of a second, so-called anodic,electrochromic layer which is also capable of reversibly insertingcations, and finally a second electrically conductive layer.

With regard to the nature of the electrically conductive layers of thedevice, there are two possible variants. It is possible to use materialsbased on doped metal oxides, such as fluorine-doped tin oxide F:SnO₂ ortin-doped indium oxide ITO. It is also possible to use layers of metals,or of metal alloys, for example based on gold Au, silver Ag or aluminiumAl. Since the device generally possesses two electrically conductivelayers, they may both be metal layers, or they may both be based ondoped oxides, or one may be based on metals and the other based on dopedoxides. It is also possible to superpose several electrically conductivelayers of different types, for example a doped-oxide layer associatedwith at least one metal Layer in a stack of the ITO/Ag or Au/ITO type,for example.

These layers (or at least one of them) may also be made of one or moreconductive polymers.

In order to form the layer of cathodic electrochromic material, amaterial, or a mixture of materials, chosen from the group comprisingtungsten oxide WO₃, molybdenum oxide MoO₃, vanadium oxide V₂O₅, niobiumoxide Nb₂O₅, titanium oxide TiO₂, a “cermet” material (a combination ofmetallic and ceramic material, especially in the form of metal particlesin a ceramic matrix) such as WO₃/Au or WO₃/Ag, and a mixture of tungstenand rhenium oxides WO₃/ReO₃, may be chosen. These materials areespecially suitable in the case of the reversible insertion of lithiumions. If the device operates by the reversible insertion of protons, thesame materials may be used, but this time in hydrated form.

In order to form the layer of anodic electrochromic material, a materialwhich satisfies the formula M_(x)A_(y)U_(z), where M is a transitionmetal, A is the ion used for the reversible insertion, for example analkali metal or a proton, and U is a chalcogen, such as oxygen orsulphur, may be chosen.

It may, especially in the case of the insertion of proton ions H⁺, be acompound or a mixture of compounds belonging to the group comprisingLiNiO_(x), IrO_(x)H_(y), IrO_(x)H_(y)N_(z), NiO_(x), NiO_(x)H_(y)N_(z),RhO_(x), CoO_(x), MnO_(x) and RuO_(x). In the case of the reversibleinsertion of lithium ions Li⁺, a compound or a mixture of compoundsbelonging to the group comprising LiNiO_(x), LiMn₂O₄, Li_(x)S_(n)O_(y),IrO_(x), Li_(x)IrO_(y), Li_(x)S_(n)O_(y), NiO_(x), CeO_(x), TiO_(x),CeO_(x)—TiO_(x), RhO_(x), CoO_(x), CrO_(x), and MnO_(x) is choseninstead.

With regard to the choice of electrolyte material, there are in fact twotypes of this, as was mentioned above.

It may be a layer of aqueous liquid, such as water to which sulphuric orphosphoric acid has been added, in the case of the reversible insertionof protons and may be a layer of anhydrous liquid, such as propylenecarbonate containing a lithium salt, in the case of the reversibleinsertion of lithium ions. It may also be a layer of gel or of polymer,especially protonically conductive polymers of the type comprising asolid solution of polyoxyethylene and c phosphoric acid POE-H₃PO₄.

However, it may also be an electrolyte in the form of a solid material,especially one based on a metal oxide. According to a variant of theinvention, the system is chosen so that it contains only layers of solidmaterials. Within the context of the invention, the term “solidmaterial” should be understood to mean any material having themechanical integrity of a solid, particularly any essentially inorganicor organic material or any hybrid material, that is to say one that ispartially inorganic and partially organic, such as materials that may beobtained by sol-gel deposition from organo-inorganic precursors. Theconfiguration is then one of a so-called “all-solid” system which is anadvantage in terms of ease of manufacture. This is because, when thesystem contains an electrolyte in the form of a polymer which does nothave, for example, the mechanical integrity of a solid, this requires infact the manufacture, in parallel, of two “half-cells” each consistingof a carrier substrate coated with a first electrically conductive layerand then with a second, electrochemically active layer, these twohalf-cells then being joined together with the electrolyte insertedbetween them. With an “all-solid” configuration, the manufacture issimplified since all the layers of the system may be deposited, oneafter the other, on a single carrier substrate. Thus all the operationsfor manufacturing the glazing are simplified since there is now only asingle substrate intended to receive layers instead of two.

Furthermore, whether the electrolyte is a “solid” electrolyte or not, itmay comprise a layer made of an ionically conductive material capable ofreversibly inserting the ions, but the degree of oxidation of which ismaintained essentially constant. It may especially be a material havingelectrochromic properties, as described in the aforementioned PatentEP-97/400702.3.

The functional system of the element according to the invention maytherefore be placed either between two substrates, or on a singlesubstrate, more particularly in the case of an “all-solid” system. Therigid carrier substrates are preferably made of glass, acrylic polymer,polycarbonate or certain polyurethanes. The carrier substrates may alsobe soft, flexible and intended to be laminated to rigid substrates; itmay be a soft polycarbonate, a polyethylene terephthalate (PET), etc.The lamination may be carried out with intercalated sheets of polymer ofthe thermoplastic type, such as polyvinyl butyral (PVB), ethylene-vinylacetate (EVA) or certain polyurethanes. With no lamination carried out,the system may also be provided with a protective varnish or film, asmentioned above.

Such glazing may thus have a “monolithic” structure, that is to saycomprises a single rigid substrate, or a plurality of rigid substrates,a laminated and/or multiple-glazing structure, or else a so-calledasymmetric glazing structure with an external plastic layer, especiallybased on polyurethane, which structure is especially described inPatents EP-191,666, EP-190,953, EP-241,337, EP-344,045, EP-402,212,EP-430,769, and EP-676,757.

By way of example, the glazing according to the invention may thus havea structure or sequence of the type:

antireflection coating/glass 1/coating attenuating or modifying thecolour in reflection/functional system/intercalated sheet of polymer ofthe PU type/glass 2

This system may also be combined with another glass in order to form adouble-glazing unit. It is also possible to provide an intercalatedsheet of polymer of the PU type and another glass between the glass 1and the coating attenuating the colour in reflection: it is thuspossible to appose one structure (antireflection coating/glass 1) withanother structure (functional system/coating attenuating thecolour/glass), these structures being laminated with a sheet of polymer.

Further details, and advantageous characteristics of the inventionemerge from the description given below of various non-limitingembodiments, with reference to the appended drawing which shows:

FIG. 1: electrochromic glazing having a laminated structure in crosssection

This FIGURE is extremely schematic and does not respect the proportionsbetween the various elements shown, so as to make it easier tounderstand. In particular, all the electrical connections, which areknown per se, are not shown.

The rigid substrates used for all the following examples are substratesmade of silicon-soda-lime glass 4 mm in thickness (their thickness mayin fact be chosen especially within the 0.7 to 6 mm range).

These are so-called “clear” glass substrates sold by Saint-GobainVitrage under the name Planilux.

EXAMPLE 1

FIG. 1 shows electrochromic glazing having a laminated structurecomprising two glass plates in a configuration suitable, for example, tobe used as the display screen of a flat-screen television: it shows twoclear glass plates 1 and an electrochromic functional system 3 of the“all-solid” type, consisting of the stack of the following functionallayers and a sheet of polyurethane 13:

-   -   a first, electrically conductive layer 4 made of F:SnO₂ 500 nm        in thickness;    -   a first layer 5 of anodic electrochromic material made of        iridium oxide IrO_(x) (hydrated) 30 nm in thickness (it could be        replaced with a layer of hydrated nickel oxide);    -   a layer 6 of hydrated tantalum oxide Ta₂O₅.H_(x) 5 nm in        thickness, having a tie-layer function;    -   a layer 7 of tungsten oxide 200 nm in thickness;    -   a second layer 8 of hydrated tantalum oxide 200 nm in thickness;    -   a second layer 9 of cathodic electrochromic material based on        tungsten oxide H_(x)WO₃ 380 nm in thickness;    -   a second layer 10 of ITO 280 nm in thickness.

Between the electrically conductive layer 4 and the glass 2 there is acoating 11 whose function is to attenuate the colour of the glazing inreflection: it is a layer of silicon oxycarbide SiOC having an index ofapproximately 1.7 and a geometrical thickness of approximately 50 to 55nm (deposited in a known manner by CVD on the glass 2). Its index isthus intermediate between those of the materials which surround it,namely that of the glass 1 (approximately 1.5) and that of the layer 4of F:SnO₂ (approximately 2).

Deposited on the external face of the glass 2 is an antireflectioncoating 12 composed of the succession of the following layers (startingfrom the surface of the glass 2):

-   -   SnO₂(19 nm)/SiO₂(33 nm)/Nb₂O₅(115 nm)/SiO₂(88 nm)

The coating was deposited in a known manner on the glass 2 bymagnetic-field-assisted reactive sputtering in the presence of oxygenusing suitable metal/silicon targets.

The coating 12/glass 2/coating 11/functional system 3 assembly is thenlaminated to the glass 1 by means of a sheet of 13 of organic polymer ofthe polyurethane type having a thickness of at least 1.24 mm.

The glazing is mounted so that the glass 2 is the glass facing theoutside of the screen.

It appears that by combining the two types of optical coatings 11 and 12with the functional system 3, it is possible to shift the accessibleT_(L) range to higher vales and to reduce the intensity of the residualcolour, in reflection, in the bleached state and in the coloured state.

EXAMPLE 2

An Example 2 was produced using the same coatings 11 and 12 and the samefunctional system 3 on the same glass 2. Thereafter, the only differenceis the way in which the glass is mounted: in this case, the final ITOlayer 10 of the functional system has been simply surmounted by avacuum-deposited layer of polyparaxylylene varnish. This thus results ina single-glass structure of the type: coating 12/glass 1/coating11/functional system 3/varnish.

EXAMPLE 3

An Example 3 was produced in a manner similar to Example 1. Only some ofthe thicknesses of the layers of the electrochromic system differslightly. Furthermore, the layer 6 of hydrated tantalum oxide wasomitted. The stack of the electrochromic system in this Example 3 istherefore as follows:

-   -   a first, electrically conductive layer 4′ of F:SnO₂ 500 nm        thickness;    -   a first layer 5′ of anodic electrochromic material made of        iridium oxide IrO_(x) (hydrated) 37 nm in thickness (it could be        replaced with a layer of hydrated nickel oxide);    -   a layer 7′ of tungsten oxide 100 nm in thickness;    -   a second layer 8′ of hydrated tantalum oxide 100 nm in        thickness;    -   a second layer 9′ of cathodic electrochromic material based on        tungsten oxide H_(x)WO₃ 280 nm in thickness;    -   a second layer 10′ of ITO 270 nm in thickness.

On he other hand, in the case of the coating 11 and the coating 12 themounting of the electrochromic system is identical to that in Example 1.

EXAMPLE 4

An Example 4 was produced like Example 3, apart from the fact that, inthis example, there is no antireflection coating 12.

It was confirmed that the optical properties of the glazing wereimproved when at least one coating (coating 11) attenuating the colouror an antireflection coating (coating 12) was provided, the maximumimprovement was obtained by using both types of coating together. It ispossible to provide a second antireflection coating (so that each of theexternal faces of the external substrates 1 and 2 is treated).

The following optical properties of Examples 3 and 4 in the bleachedstate (+1.2 V supply) and in the coloured state (−1.6 V supply) werecompared:

-   -   the light transmission T_(L) (%);    -   the values of a*_(T) _(L) and b*_(T) _(L) in the (L*,a*,b*)        system in transmission;    -   the light reflection R_(L1) on the “internal side” and the        corresponding a* and b* values;    -   the light reflection R_(L2) on the “external side” and the        corresponding a* and b* values.

This data is given in Table 1 below.

Table 2 below gives data on the energy properties of these same twoexamples, namely the energy transmission T_(E)(%), the energy reflectionR_(E1) (on the external side) and R_(E2) (on the internal side).

TABLE 1 EXAMPLE 4 EXAMPLE 3 T_(L) R_(L1) R_(L2) T_(L) R_(L1) R_(L2) −1.6V +1.2 V −1.6 V +1.2 V −1.6 V +1.2 V −1.6 V +1.2 V −1.6 V +1.2 V −1.6 V+1.2 V 14.6 72.0 3.3 9.4 3.4 10.0 16.0 79.9 4.6 4.6 2.3 5.7 a*-2.0 −3.01.3 6.9 −0.4 3.6 −2.8 −3.3 0.1 14.1 −2.1 8.5 b*-23.6 5.7 1.0 −3.8 4.6−1.7 −23.2 6.4 −7.7 −12.2 6.3 −5.3

TABLE 2 EXAMPLE 4 EXAMPLE 3 T_(E) R_(E1) R_(E2) T_(E) R_(E1) R_(E2) −1.6V +1.2 V −1.6 V +1.2 V −1.6 V +1.2 V −1.6 V +1.2 V −1.6 V +1.2 V −1.6 V+1.2 V 10.0 61.2 3.1 9.5 5.4 13.2 10.2 60.2 9.6 12.8 16.0 15.2

Also measured were their solar factors SF (the solar factor is the ratiobetween the total energy entering the room through the glazing to theincident solar energy): p1 for Example 3: the SF is 33% in the colouredstate (−1.6 V) and 73% in the bleached state (+1.2 V);

-   -   for Example 4: the SF is 32% in the coloured state and 67% in        the bleached state.

It may be seen from this data that, in the case of Example 3 accordingto the invention, it is possible to achieve a wider light transmissionrange and, in particular, to achieve a T_(L) of almost 80% in thebleached state. The energy transmission in the bleached state of Example3 is also lower than that of Example 4 and the energy reflections arehigher, whether in the coloured state or in the bleached state. Example4, which has only the anti-colour coating, already shows an improvementover standard electrochromic glazing, especially with regard to R_(L1)and R_(L2) colorimetry in reflection. But Example 3, in which anantireflection coating has been added, allows the T_(L) range to bebroadened towards higher values and allows the glazing to be made moreeffective from the standpoint of the filtration of thermal, especiallysolar, radiation.

1. Glazing comprising (a) at least one electrochromic system havingvariable optical and/or energy properties, (b) at least one coating foradjusting the optical appearance conferred on the said glazing by thesaid system, said at least one coating having antireflection propertiesin the visible, wherein said coating having antireflection properties isdeposited on at least one of the external faces of said glazing andcomprises a stack of thin layers having alternately high and lowreflective indices or a graded-refractive-index layer, and (c) at leastone coating for attenuating/modifying the color of the glazing inreflection, wherein the coating (c) is in contact with the electricallycontrollable system (a), in the form of a thin layer having a refractiveindex intermediate between those of the materials with which it is incontact on each of its faces.
 2. Glazing according to claim 1,additionally comprising a carrier substrate and a primer/tie-layercoating for the electrochromic system (a) with respect to the carriersubstrate.
 3. Glazing according to claim 2, wherein the carriersubstrate comprises a polymeric/plastic material.
 4. Glazing accordingto claim 1, which comprises a coating having hydrophilic/antimistingproperties or having hydrophobic/anti-rain properties on at least one ofits external faces.
 5. Glazing according to claim 4, wherein the coatinghaving hydrophobic properties includes at least one layer comprising acomposition having at least one fluoroalkoxysilane, the alkoxyfunctional groups of which are directly linked to the silicon atom, asystem of one or more aqueous solvents and at least one catalyst whichis an acid and/or a Brönsted base.
 6. Glazing according to claim 1,which also includes a coating having photocatalytic/antifoulingproperties.
 7. Glazing according to claim 6, wherein the coating havingphotocatalytic/antifouling properties is located on at least one of itsexternal faces.
 8. Glazing according to claim 7, wherein the coatinghaving photocatalytic/antifouling properties comprises TiO₂ at leastpartially crystallized in the anatase form.
 9. Glazing according toclaim 1, which comprises at least one coating having electromagneticscreening properties.
 10. Glazing according to claim 1, wherein theelectrochromic system (a) is a superposition of functional layers placedbetween two carrier substrates, each of the said substratesindependently being rigid, semi-rigid or flexible.
 11. Glazing accordingto claim 10, wherein the electrochromic system (a) includes, as carriersubstrate, at least one rigid substrate of which the glazing iscomposed, and/or at least one flexible carrier substrate associated bylamination, with a rigid substrate of which the said glazing iscomposed.
 12. Glazing according to claim 1, wherein the electrochromicsystem (a) is a superposition of functional layers placed on a carriersubstrate and provided with an inorganic or polymeric layer protectivefilm.
 13. Glazing according to claim 12, wherein the protective film isin the form of a lacquer or of a varnish.
 14. Glazing according to claim1, wherein the electrochromic system (a) is an all-solid electrochromicsystem.
 15. Glazing according to claim 1, wherein electrochromic system(a) is in the form of a system comprising one or morereversible-insertion materials of the electrochromic system orgasochromic system type, or in the form of an optical-valve orviologen-based system.
 16. Glazing according to claim 1, whereinelectrochromic system (a) is in the form of a liquid-crystal orcholesteric-gel system.
 17. Glazing comprising (a) at least oneelectrochromic system having variable optical and/or energy properties,(b) at least one coating for adjusting the optical appearance conferredon the said glazing by the said system, said at least one coating havingantireflection properties in the visible, wherein said coating havingantireflection properties is deposited on at least one of the externalfaces of said glazing and comprises a stack of thin layers havingalternately high and low reflective indices or a graded-refractive-indexlayer, and (c) at least one coating for attenuating/modifying the colorof the glazing in reflection, wherein the coating (c) is interposedbetween the electrochromic system (a) and a substrate for said glazing.